WO2014139442A1

WO2014139442A1 - Surgical fastener applying apparatus

Info

Publication number: WO2014139442A1
Application number: PCT/CN2014/073337
Authority: WO
Inventors: Hui Zhan; Salman KAPADIA; Kin Ying LEE; Wei Hu
Original assignee: Covidien Lp; Covidien (China) Medical Devices Technology Co., Ltd.
Priority date: 2013-03-15
Filing date: 2014-03-13
Publication date: 2014-09-18
Also published as: CN104042289A

Abstract

A surgical stapling device is provided. The device includes a housing (20); an outer tube (30) extending distally from the housing (20), a disposable staple assembly (300) releasably supported on a distal end of the outer tube (30), an approximation assembly (100) operably received within the housing (20), and a staple pusher assembly (200) extending from within the housing (20) to the staple assembly (300). The outer tube (30) includes a proximal end connected with the housing (20) and a distal end. The staple assembly (300) includes a shell (302) movably supporting a pusher back (310) and a plurality of fasteners. The pusher back (310) is movable with the shell (302) to eject the plurality of fasteners from the disposable staple assembly (300). The approximation assembly (100) includes an anvil retainer (140) configured to releasably engage an anvil assembly (50). The approximation assembly (100) is operable to approximate the anvil assembly (50) and the staple assembly (300). The staple pusher assembly (200) is releasably connected to the pusher back (310) of the staple assembly (300) and is operable to effect movement of the pusher back (310) within the shell (302) and includes at least one release tab (308b) which is movable to effect separation of the staple assembly (300) and the outer tube (30).

Description

SURGICAL FASTENER APPLYING APPARATUS

Background

1. Technical Field

The present disclosure relates to a surgical fastener applying apparatus and, more particularly, to surgical fastener applying apparatus having reusable and disposable components.

2. Discussion of Related Art

Anastomosis refers to the surgical joining of separate hollow tissue sections. Typically, an anastomosis procedure follows surgery in which a diseased or defective section of a hollow tissue structure is removed, thus requiring the joining of the remaining end sections of the tissue structure. Depending on the particular procedure being performed and/or other factors, the end sections of the tissue may be joined by circular anastomosis, e.g., end-to-end anastomosis, end- to-side anastomosis, or side-to-side anastomosis.

In a circular anastomosis procedure, the two end sections of a tubular organ are joined using a stapling apparatus that drives a circular array of staples through each of the end sections to join the end sections to one another in end-to-end relation and simultaneously cores any tissue within the newly joined hollow tissue structure to clear the passage defined by the hollow tissue structure. The apparatus can also apply other surgical such as, for example, clips or two part polymeric surgical fasteners.

A typical circular anastomosis apparatus includes an elongated shaft having a handle portion at a proximal end and a staple holding component at a distal end. An anvil assembly including an anvil rod and an attached anvil head is mounted to the distal end of the elongated shaft adjacent the staple holding component. In use, the end portions to be joined are clamped between the anvil head and the staple holding component. The clamped end portions are then joined to one another by driving one or more staples from the staple holding component, through the tissue, and into the anvil head to form the staples about the tissue. In some such apparatus, a knife is provided to cut the tissue which has been joined by the staples. Examples of such circular anastomosis apparatuses are described in U.S. Patent Nos. 7,857,187 to Milliman ("the Milliman Ί87 patent") and 6,945,444 to Gresham et al. ("the Gresham '444 patent"), the entire contents of which are hereby incorporated by reference herein in their entireties.

Typically, surgical stapling apparatus for performing circular anastomosis procedures are disposable after a single use. A need exists for a surgical stapling apparatus that includes reusable components and is not overly complex and is configured to facilitate sterilization after use in a surgical procedure.

SUMMARY

Accordingly, a surgical stapling device is provided. In one aspect, the device includes a housing, an outer tube extending distally from the housing, a disposable staple assembly releasably supported on a distal end of the outer tube, an approximation assembly operably received within the housing, and a staple pusher assembly extending from within the housing to the staple assembly. The outer tube includes a proximal end connected with the housing and a distal end. The staple assembly includes a shell movably supporting a pusher back and a plurality of fasteners. The pusher back is movable with the shell to eject the plurality of fasteners from the disposable staple assembly. The approximation assembly includes an anvil retainer configured to releasably engage an anvil assembly. The approximation assembly is operable to approximate the anvil assembly and the staple assembly. The staple pusher assembly is releasably connected to the pusher back of the staple assembly and is operable to effect movement of the pusher back within the shell and includes at least one release tab which is movable to effect separation of the staple assembly and the outer tube.

In an embodiment, the approximation assembly and the staple pusher assembly are selectively removable from within the housing. The housing may include a first housing section and a second housing section releasably coupled to the first housing section. The first and second housing sections may be configured to be separated to provide access to an interior of the housing. The staple pusher assembly may be configured to be sterilized. The staple pusher assembly may include a pusher linkage for effecting ejection of the staples from the staple assembly.

In some embodiments, the outer tube may include at least one opening and the shell may include at least one engagement member positioned to be received within the at least one opening to releasably secure the shell to the outer sleeve. Each of the engagement members may include a release tab which is depressible to effect disengagement of the shell and the outer tube. The engagement member may include two engagement members and the opening may include two openings, each opening may be configured to receive a respective one of the engagement members. The pusher back may include at least one cantilevered engagement member and the staple pusher assembly may include a pusher tube defining at least one opening positioned to receive the at least one engagement member to releasably secure the pusher back to the pusher tube. The cantilevered engagement member may include two cantilevered engagement members and the opening may include two openings, each of the openings may be positioned to receive a respective one of the engagement members. The pusher back may include a cantilevered engagement member and the staple pusher assembly may include a pusher tube defining an opening positioned to receive the cantilevered engagement member to releasably secure the pusher back to the pusher tube. The engagement member of the shell may be positioned about the cantilevered engagement member of the pusher back such that the release tab is depressible to move the engagement member of the shell into contact with the cantilevered engagement member of the pusher back to deflect the cantilevered engagement member of the pusher back inwardly to effect disengagement of the pusher back from the pusher tube.

In accordance with another aspect of the present disclosure, a surgical stapling device is provided which includes a housing and an approximation assembly operably received within the housing. The approximation assembly includes a rotatable sleeve defining an internal notch, a screw configured to be longitudinally advanced and retracted relative to the rotatable sleeve and a first spring disposed distal of the screw for biasing the screw proximally. The screw includes a plurality of helical thread sections and an unthreaded space between each of the helical thread sections. Each of the helical thread sections is configured to engage the internal notch in the rotatable sleeve. The first spring urges a proximal face of an adjacent helical thread section into engagement with the internal notch as each helical thread section disengages the internal notch. The surgical stapling device may include a second spring disposed proximal of the screw for biasing the screw distally. The force applied to the screw by the first spring may be greater then the force applied to the screw by the second spring.

In accordance with another aspect of the present disclosure, a surgical stapling device is provided which includes a housing, an outer tube extending distally from the housing, and a staple pusher assembly extending from within the housing to the staple assembly. The outer tube has a proximal end connected with the housing and a distal end. The staple pusher assembly is releasably connected to a pusher back of a staple assembly and operable to effect movement of the pusher back within a shell of the staple assembly. The staple pusher assembly includes a pusher linkage for effecting ejection of the staples from the staple assembly. The pusher linkage includes a plurality of straight pusher tubes configured to articulate relative to each other.

Brief Description of the Drawings

Various embodiments of the presently disclosed surgical fastener applying apparatus will now be described herein with reference to the accompanying figures wherein:

FIG. 1 is a perspective view of an embodiment of the presently disclosed surgical stapling device including an anvil assembly in the unapproximated position;

FIG. 2 is a perspective side view of the surgical stapling device shown in FIG. 1, without an anvil assembly;

FIG. 3 is another perspective view of the surgical stapling device shown in FIG. 1 without an anvil assembly;

FIG. 4 is an exploded perspective view of the surgical stapling device shown in FIG. 1;

FIG. 5 is a side view showing internal components of a first handle section of the surgical stapling device of FIG. 1;

FIG. 6 is side view showing internal components of a second handle section of the surgical stapling device of FIG. 1;

FIG. 7 is a perspective view of the approximation assembly of the surgical stapling device of FIG. 1;

FIG. 8 is an enlarged view of the indicated area of detail shown in FIG. 7;

FIG. 9 is a perspective view with parts separated of the approximation assembly shown in

FIG. 7; FIG. 10 is a perspective side view of an alternative embodiment of an approximation assembly according to the present disclosure mounted with a housing section;

FIG. 11 is a perspective view of the approximation assembly of FIG. 10;

FIG. 12 is a cross-sectional side view of the approximation assembly and housing section of FIG. 10;

FIG. 13 is an enlarged perspective view of a portion of the housing of FIG. 10;

FIG. 14 is a perspective view of a staple pusher assembly of the surgical stapling device shown in FIG. 1;

FIG. 15 is an enlarged view of the indicated area of detail shown in FIG. 14;

FIG. 16 is a perspective view with parts separated of the staple pusher assembly shown in FIG. 14;

FIG. 17 is an enlarged view of the indicated area of detail shown in FIG. 16, with the pusher tubes separated;

FIG. 18 is an enlarged view of the indicated area of detail shown in FIG. 16, with the pusher tubes connected;

FIG. 19 is a cross-sectional side view of the elongated body portion and head portion of the surgical stapling device of FIG. 1;

FIG. 20 is an enlarged view of a portion of FIG. 19;

FIG. 21 is a perspective view with parts separated of a staple assembly of the surgical stapling device of FIG. 1;

FIG. 22 is an enlarged perspective view of the indicated area of detail shown in FIG. 4; FIG. 23 is an enlarged perspective view of the indicated area of detail shown in FIG. 4; FIG. 24 is a perspective view of the staple assembly shown in FIG. 21 being attached to an outer tube of the surgical stapling device;

FIG. 25 is a cross-sectional side view of the staple assembly shown in FIG. 21, operably connected to the outer tube of FIG. 24;

FIG. 26 is a perspective side view of the staple assembly and outer tube shown in FIG. 25;

FIG. 27 is a perspective side view of the staple assembly shown in FIG. 26, with the outer tube removed;

FIG. 28 is a perspective side view of the staple assembly shown in FIG. 27, with the shell removed;

FIG. 29 is a perspective side view of a pusher back of the staple assembly shown in FIG.

28;

FIG. 30 is a cross-sectional side view of the staple assembly and outer tube shown in FIG. 25, separated from one another;

FIG. 31 is a cross-sectional side view of the staple assembly and outer tube shown in FIG. 30, operably connected to one another;

FIG. 32 is a cross-sectional side view of the staple assembly and outer tube shown in FIG. 30, with the staple assembly selectively secured with the outer tube;

FIG. 33 is a perspective view of the anvil assembly shown in FIG. 1;

FIG. 34 is another perspective view of the anvil assembly shown in FIG. 1;

FIG. 35 is a cross-sectional side view of the surgical stapling device of FIG. 1;

FIG. 36 is an enlarged cross-sectional view of the indicated area of detail shown in FIG.

25; FIG. 37 is a cross-sectional side view of a handle portion of the surgical stapling device of FIG. 1, in an unapproximated position;

FIG. 38 is a cross-sectional side view taken along lines 32-32 shown in FIG. 31;

FIG. 39 is an enlarged cross-sectional view of the indicated area of detail shown in FIG.

37;

FIG. 40 is a cross-sectional side view of the handle portion shown in FIG. 37, in an approximated position;

FIG. 41 is a cross-sectional side view of a body portion and a head portion of the surgical stapling device shown in FIG. 1;

FIG. 42 is a cross-sectional side view of the handle assembly shown in FIG. 37, during actuation of the staple pusher assembly shown in FIG. 14; and

FIG. 43 is a cross-sectional side view of the body portion and the head portion shown in FIG. 35, during actuation of the staple pusher assembly.

Detailed Description of Embodiments

Embodiments of the presently disclosed surgical stapling device will now be described in detail with reference to the drawings in which like reference numerals designate identical or corresponding elements in each of the several views. Throughout this description, the term "proximal" will refer to the portion of the instrument closer to the operator and the term "distal" will refer to the portion of the instrument further from the operator.

FIGS. 1-43 illustrate an embodiment of the presently disclosed surgical fastener applying apparatus designated generally as surgical stapling device 10. The stapling device 10 is intended to be resterilized and reused. As will become apparent from the following disclosure, stapling device 10 is constructed as a plurality of assemblies that are selectively retained within a housing. The construction of stapling device 10 facilitates the sterilization of surgical device 10 between uses.

With reference initially to FIGS. 1-3, stapling device 10 includes a proximal handle portion 12, an elongated curved central body portion 14 and a distal head portion 16. Alternately, in some surgical procedures, e.g., the treatment of hemorrhoids, it may be desirable to have a substantially straight, shortened, central body portion. The length, shape and/or the diameter of any of handle portion 12, body portion 14 and head portion 16 may also be varied to suit a particular surgical procedure.

With reference now to FIGS. 1-4, handle portion 12 of stapling device 10 includes a housing 18 which supports proximal portions of an approximation assembly 100 and a staple pusher assembly 200, as will be discussed in further detail below. Body portion 14 of stapling device 10 includes an outer tube 30 which supports elongated portions of approximation assembly 100 and staple pusher assembly 200. Head portion 16 of stapling device 10 includes an anvil assembly 50 operably connected with a distal end of approximation assembly 100 and a staple assembly 300 supported on a distal end of outer tube 30 and operably connected with a distal end of staple pusher assembly 200. To allow for repeated use of surgical stapling device 10, each component of surgical stapling device 10 must either be sterilized or replaced. In an embodiment, each of housing 20, outer tube 30, approximation assembly 100 and staple pusher assembly 200 are configured to be reused while staple assembly 300 is configured to be replaced. As such, except where otherwise noted, the components of surgical stapling device 10 are generally formed from thermoplastics including polycarbonates, and metals including stainless steel and aluminum, that are suited to withstand repeated sterilization procedures, e.g., autoclaving. With particular reference now to FIGS. 4-6, housing 20 of handle portion 12 includes handle sections 20a, 20b. Handle sections 20a, 20b are configured to be selectively secured together to permit access to approximation assembly 100 and staple pusher assembly 200 and to facilitate sterilization of housing 20. Handle sections 20a, 20b may be secured together using screws, nuts and bolts, snap-fit connectors or any other suitable securement technique. In an embodiment, handle sections 20a, 20b are releasably secured together in a fashion that permits ready separation of handle sections 20a and 20b to facilitate sterilization of stapling device 10. In another embodiment, the handle sections 20a and 20b are attached permanently by a pin and remain attached with the pusher during cleaning and re-assembly. Cushioned and/or resilient slip resistant portions such as a grip (not shown) may be fastened to or included as part of handle sections 20a, 20b. The slip resistant grip may be formed over handle sections 20a, 20b using an overmolding procedure and may be formed from neoprene or rubber. Alternately, other suitable materials, e.g., elastomeric materials, and joining techniques may be employed to secure a slip resistant portion to handle sections 20a, 20b.

Referring also to FIGS. 1-4, as noted above, an outer tube 30 extends distally from housing 20. A pair of openings 31 (FIG. 4) formed in a proximal end 30a of outer tube 30 are dimensioned to receive protrusions (not shown) formed on the internal wall of housing 20 to facilitate attachment of outer tube 30 to handle portion 12. A distal end 30b of outer tube 30 is configured for operable connection with a proximal end of staple assembly 300 (FIG. 1). In particular, distal end 30b of outer tube 30 includes a pair of openings and slots 33a, 33b (FIG. 22) configured for selective connection with shell 302 of stapling assembly 300. Distal end 30b further includes an orientation slot 35 configured to orient shell 302 relative to distal end 30b of outer tube 30. Approximation assembly 100 will now be described in detail with reference to FIGS. 4-9. Approximation assembly 100 includes an approximation knob 102, a rotatable sleeve 110, a drive screw 120, first and second screw extensions 130a, 130b (collectively, screw extension 130), an anvil retainer 140, a screw stop 150 and a cam mechanism 160 (FIG. 8). Rotatable sleeve 110 includes a substantially cylindrical hollow body portion 112 and a substantially cylindrical collar 114 which together define a central bore 113 (FIG. 8). Collar 114 has an annular groove 114a formed thereabout which is dimensioned to receive an inwardly extending flange 22 (FIG. 5) formed on an inner wall of handle sections 20a, 20b. Engagement between groove 114a and flange 22 axially fixes sleeve 110 within housing 20 while permitting rotation of sleeve 110 in relation to housing 20. A pin 116 (FIG. 9) extends radially through cylindrical collar 114 of sleeve 110 and into central bore 113. A proximal end of body portion 112 of rotatable sleeve 110 extends through an opening 21 in a proximal end of housing 20. A pair of diametrically opposed elongated ribs 118 (FIG. 9) are positioned or formed on the outer surface of body portion 112. Approximation knob 102 includes a pair of internal slots 103 positioned to receive ribs 118 of sleeve 112 to rotatably fix sleeve 112 to knob 102, such that rotation of knob 102 causes concurrent rotation of sleeve 110.

With reference still to FIGS. 4-9, a proximal half 120a of screw 120 includes a helical channel 121 and is dimensioned to be slidably positioned within central bore 113 of rotatable sleeve 110. A distal end 120b of screw 120 may include an annular recess (not shown) dimensioned to receive a seal member (not shown) for providing a fluid tight seal between the outer surface of screw 120 and the inner surface of pusher linkage 220. Pin 116 of sleeve 110 extends radially through cylindrical collar 114 into helical channel 121 of screw 120. Since sleeve 110 is axially fixed with respect to housing 20, rotation of sleeve 110 about screw 120 causes pin 116 to move along channel 121 of screw 120 to effect axial movement of screw 120 within housing 20. Although shown having helical channel 121 configured to receive pin 116, it is envisioned that screw 120 may include a helical thread on an outer surface thereof configured to be received within channel or groove formed on an inner surface of sleeve 110.

Distal end 120b of screw 120 defines a transverse slot 123 and a throughbore 125. Transverse slot 123 is configured to receive a proximal end of screw extension 130 and through bore 125 is configured to receive a pin 126 for securing screw extension 130 to screw 120. Top and bottom screw extensions 130a, 130b each include a proximally located flexible flat band portion 132a, 132b (collectively, flat band portions 132), respectively, and a distally located flat band portion 134a, 134b (collectively, flat band portions 134), respectively. Alternately, it is envisioned that screw extensions 130a, 130b may have other than a band configuration. For example, screw extensions 130a, 130b may be semi-circular or circular in cross-section. The flexibility of top and bottom screw extensions 130a, 130b permits movement of screw extensions 130a, 130b through curved elongated body portion 14. The proximal end of each of flat band portions 132a, 132b includes a hole 133a, 133b (collectively, holes 133), respectively, dimensioned to receive pin 126 for securing the proximal end of screw extension 130 within transverse slot 123 of screw 120. Alternately, other fastening techniques may be used to secure flat band portion 132 to screw 120, e.g., welding, crimping, etc.

Distally located flat band portion 134 of screw extensions 130 are dimensioned to be received within a transverse slot 141 formed in a proximal end 142 of anvil retainer 140 to fasten anvil retainer 140 to distal end 134 of screw extensions 130. In an embodiment, a pair of pins 144a, 144b extends through the proximal end of anvil retainer 140 and the distal end of flat band portion 134 to secure screw extensions 130 to anvil retainer 140. Alternately, flat band portions 134 may be brazed or welded within slot 141 or other fastening techniques may be used to secure flat band portions 134 of screw extensions 130 to anvil retainer 140, e.g., screws, crimping, etc. Anvil retainer 140 includes an annular protrusion 146 which is configured to releasably engage anvil assembly 50 in a manner to be discussed in detail below. Alternately, protrusion 146 need not be annular or may include different attachment structure, e.g., recesses, grooves, etc.

Referring again to FIGS. 4-9, when approximation knob 102 is manually rotated, rotatable sleeve 110 is rotated about proximal end 120a of screw 120 to move pin 116 along helical channel 121 of screw 120. Since sleeve 1 10 is axially fixed to housing 20, as pin 116 is moved through channel 121, screw 120 is advanced or retracted within housing 20. As a result, top and bottom screw extensions 130a, 130b, which are fastened at their proximal ends to distal end 124 of screw 120, and at their distal ends to anvil retainer 140, are moved axially within elongated body portion 14. Since anvil assembly 50 is secured to the distal end of anvil retainer 150, rotation of approximation knob 102 will effect movement of anvil assembly 50 in relation to staple assembly 300 between spaced and approximated positions.

With particular reference now to FIGS. 7-9, cam adjustment member 160 is secured by a set screw 164 onto a sidewall 150a of screw stop 150 within a recess 150b formed in sidewall 150a. Cam adjustment member 160 includes a circular disc 162 having a throughbore 163. Throughbore 163 is eccentrically formed through disc 162 and is dimensioned to receive set screw 164. A smaller notch or hole 165 is also formed in disc 162 and is dimensioned to receive the tip of an adjustment tool (not shown). Recess 150b includes a forward abutment shoulder or surface 150c (FIG. 8) and a rear abutment surface 150d and is dimensioned to receive disc 162 of cam adjustment member 160 such that the outer edge of disc 162 abuts forward and rear abutment surfaces 150c, 150d. Still referring to FIGS. 7-9, set screw 164 extends through disc 162 and screw stop 150 and is received in a threaded bore 122a in proximal end 122 of screw 120 to secure screw stop 150 in an axially fixed position on screw 120. Cam adjustment member 160 functions to adjust the axial position of screw stop 150 on screw 120. More specifically, set screw 164 may be loosened to allow disc 162 to rotate within recess 150b of screw stop 150. Since disc 162 is eccentrically mounted about screw 120 and engages forward and rear abutment surfaces 150c, 150d of recess 150b, rotation of disc 162 about fixed set screw 164 will urge screw stop 150 axially along screw 120 to adjust the axial position of screw stop 150 on screw 120. For example, in an embodiment, when disc 162 is rotated in a clockwise direction, screw stop 150 moves axially in relation to screw 120 in response to engagement between the outer edge of disc 162 and rear shoulder 150d of recess 150b. Conversely, when disc 162 is rotated in a counterclockwise direction, screw stop 150 moves axially in relation to screw 120 in response to engagement between the outer edge of disc 162 and forward shoulder 150c of recess 150b.

When stapling device 10 is in a fully approximated position, i.e., anvil assembly 50 and staple assembly 300 are brought into juxtaposed alignment to define a tissue receiving clearance (FIG. 35), screw stop 150 abuts against a distal end of body portion 112 of the rotatable sleeve 110, i.e., sleeve 110 functions as a stop for approximation assembly 100 (FIG. 34). In this position, anvil assembly 50 and shell assembly 300 are spaced slightly to define a tissue receiving clearance or minimum tissue gap. By providing cam adjustment member 160, the tissue receiving clearance or minimum tissue gap may be selectively adjusted to be within a desired range by adjusting the position of screw stop 150 on screw 120. In an embodiment, cam adjustment member 160 permits adjustment of the tissue receiving clearance of ±0.045 inches, although greater or lesser adjustment capabilities are also envisioned. Typically, adjustments to the tissue receiving clearance will be made by the device manufacturer. Alternately, a hole or opening may be provided in handle portion 12 (FIG. 1) to provide direct access to adjustment member 160 to allow for on-site adjustment of the tissue receiving clearance by a surgeon or other medical professional. Adjustment member 160 may also be adjusted between uses when housing 20 is opened and approximation assembly 100 is removed from housing 20 for sterilization purposes.

With reference to FIGS. 10-13, an alternative embodiment of an approximation assembly for use in a surgical stapling device is shown generally as approximation assembly 100'. Approximation assembly 100' is substantially similar to approximation assembly 100 and will only be described as relates to the differences therebetween. Approximation assembly 100' includes a rotatable sleeve 110' defining an internal notch 115' (FIG. 12), a screw 120' having a plurality of longitudinally spaced helical thread sections 121a', 121b', 121c', 121d', 121e', 121f (collectively, helical thread 121 ') configured to selectively engage notch 115' formed on rotatable sleeve 110', and a screw stop 150' fixedly secured to screw 120'. As shown, each of helical thread sections 121b', 121c', 121d', 121e', include only a single convolution while helical thread section 121a', 121f include multiple convolutions. As will be discussed in further detail below, the multiple convolutions of helical thread section 121f permits fine approximation of anvil assembly 50 (FIG. 1) relative to staple assembly 300 (FIG. 1) as anvil assembly 50 nears full approximation. Screw 120' includes unthreaded spaces between each of helical thread sections 121a', 121b', 121c', 121d', 121e', 121f .

With particular reference to FIGS. 10 and 12, a front spring 170' is disposed between a proximal end of elongated pusher tube 230' of the staple pushing assembly and screw stop 150' to bias screw 120' proximally to urge a proximal face of adjacent helical thread section into notch 115'. Similarly, a back spring 180' is disposed within rotatable sleeve 110' and is configured to bias screw 120' distally to urge a distal face of an adjacent helical thread section into internal notch 115'. The force applied to screw 120' by front spring 170' is greater then the force applied to screw 120' by back spring 180'. In this manner, when both front spring 170' and back spring 180' are acting on screw 120', front spring 170' overpowers back spring 180 such that screw 120' is biased proximally. Thus, when both front spring 170' and back spring 180' are acting on screw 120', only retraction of screw 120' can be effected.

During rotation of rotatable sleeve 110' to retract screw 120' to effect the approximation of anvil assembly 50 (FIG. 1) towards staple assembly 300 (FIG. 1), rotatable sleeve 110' is rotated to effect passage of each successive helical thread section through notch 115'. When an unthreaded space between each helical thread section 121a', 121b', 121c', 121d', 121e', 121f becomes aligned with internal notch 115' of rotatable sleeve 110', first spring 170', against the bias of back spring 180', moves screw 120' proximally until the next successive helical thread section becomes engaged with internal notch 115'. As sleeve 110' is continually rotated, each successive helical section will pass through notch 115' and front spring 170' will retract screw 120' the length of the unthreaded spaces until the next successive helical thread section engages internal notch 115'. In this manner, anvil assembly 50 (FIG. 1) may be approximated towards staple assembly 300 (FIG. 1) at a greater rate than if helical thread 121 ' extended the entire length of screw 120'. Such a configuration also lessens the burden on the clinician operating the stapler as fewer rotations of rotatable sleeve 110' are required for full approximation of anvil assembly 50. The configuration and spacing of helical thread section 121f permits fine approximation of anvil assembly 50 (FIG. 1) relative to staple assembly 300 (FIG. 1) as anvil assembly 50 nears full approximation. The closer helical thread sections 121f are spaced, the finer the approximation.

With particular reference now to FIGS. 12 and 13, front spring 170' includes a slider 172' configured to permit the retraction of front spring 170' to a position disengaged from screw 120'. Slider 172' may be integrally formed with front spring 170'. Alternatively, slider 172' may be constructed separate from front spring 170'. As seen in FIG. 13, housing 20' includes a slot 21 ' and a notch 23' formed on a distal end of slot 21 '. Slot 21 ' is configured to receive an outer end 172a' of slider 172' therethrough. Notch 23' is configured to selectively receive outer end 172a' of slider 172' when front spring 170' is in a retracted position to lock front spring 170' in the retracted position. Retraction of front spring 170' disengages front spring 170' from screw stop 150' thereby removing the proximal force applied by front spring 170' against screw stop 150' which urges screw 120' proximally. As such, when slider 172' is operated to retract front spring 170', the force provided by back spring 180' is no longer overpowered by front spring 170' and back spring 180' biases screw 120' distally.

During rotation of rotatable sleeve 110' to advance screw 120' to cause anvil assembly 50 (FIG. 1) to be unapproximate in relation to staple assembly 300 (FIG. 1), when an unthreaded space between each helical thread section 121a', 121b', 121c', 121d', 121e', 121f becomes aligned with internal notch 115' of rotatable sleeve 110', back spring 180' moves screw 120' distally until the next successive helical thread section becomes engaged with internal notch 115'. As sleeve 110' is continually rotated, each successive helical section will pass through internal notch 115' and back spring 180' will advance screw 120' the length of the unthreaded spaces until the next successive helical thread section engages internal notch 115'. In this manner, anvil assembly 50 (FIG. 1) may be unapproximated relative to staple assembly 300 (FIG. 1) at a greater rate than if helical thread 121 ' extended the entire length of screw 120'. As discussed above, such a configuration lessens the burden on the clinician operating the stapler as few rotations are required to unapproximate anvil assembly 50. Slider 172' may be locked or unlocked throughout use of the surgical stapling device to permit the approximation and unapproximation of anvil assembly 50.

Staple pushing assembly 200 will now be described with reference to FIGS. 14-20. Staple pusher assembly 200 includes firing trigger 202, a firing link 210 and a pusher linkage 220. Pusher linkage 220 includes an elongated pusher tube 230, a pusher link tube 240 and a pusher end tube 250, and is configured for transferring force from proximal handle portion 12 (FIG. 1) to distal head portion 16. Although shown to include three straight pipe tubes, it is envisioned that pusher linkage 220 may include two or more pipe tubes, e.g., four, five, etc. It is also envisioned that pusher linkage 220 may include at least one curved or nonstraight tube. It is also envisioned that pusher linkage 220 may include at least one flexible tube. Firing trigger 202 includes a body portion 204 which may support cushioned gripping surface (not shown) formed of neoprene, rubber or the like. The cushioned gripping surface provides a non-slip cushioned surface to make actuation of stapling device 10 more comfortable to a surgeon. Alternatively, firing trigger 202 may be formed of perforated stainless-steel or other metal to facilitate sterilization. The distal end of body portion 204 (FIG. 14) of trigger 202 is pivotally connected to a pair of flanges 224a, 224b formed on proximal end 230a of elongated pusher tube 230 of pusher linkage 220 by a pivot member 206. Alternatively, pusher linkage 220 may include a coupling member (not shown), integrally formed with or fixedly secured to, end 230a of pusher tube 230 for pivotally connecting trigger 202 with pusher linkage 220. Firing link 210 has a distal end 212 pivotally secured to body portion 204 of trigger 202 by a pivot member 208 and a second end 214 pivotally secured within slots 23a, 23b (FIGS. 5 and 6) formed between stationary handle half-sections 20a, 20b, respectively, of housing 20 by pivot member 216. Pivot member 216 is free to move vertically within slots 23a, 23b. Although not shown, it is contemplated that a spring may be supported within housing 20 to urge pivot member 216 downwardly towards the bottom of slot 23. A more detailed description of a spring configured for supporting pivot member 216 is provided in the Milliman Ί87 patent, the content of which was previously incorporated by reference herein in its entirety. As shown, body portion 204 of trigger 202 may further include a pair of abutments 205a, 205b which are positioned to engage the distal end of a trigger lock (not shown) to prevent actuation of trigger 202 prior to approximation of stapling device 10. A more detailed description of a trigger lock configured for use with stapling device 10 and its operation is provided in the Milliman Ί87 patent.

A pair of extensions 232a, 232b extends radially outwardly from proximal end 230a of elongated pusher tube 230. Extensions 232a, 232b are dimensioned to slide along channels 25a, 25b (FIGS. 5 and 6) formed along the internal walls of housing 20 to maintain proper alignment of pusher linkage 220 within housing 20 during firing of stapling device 10.

Referring to FIGS. 16-20 and 23, distal ends 230b, 240b of each of elongated pusher tube 230 and pusher link tube 240, respectively, include a flange 234, 244, respectively, forming substantially semispherical recesses 233, 243, respectively, and define a pair of opposed longitudinal slots 235, 245, respectively. Flanges 234, 244 are each configured to receive a substantially semi-spherical portion 242, 252, respectively, of proximal end 240a of pusher link tube 240 and proximal end 250a of pusher end tube 250, respectively, to form a bearing. The bearing formed by the configuration of recesses 233, 243 and substantially semi-spherical portions 242, 252 (FIG. 14) permit articulation between elongated pusher tube 230 and pusher link tube 240 and between pusher link tube 240 and pusher end tube 250. In an embodiment, elongated pusher tube 230 is configured to longitudinally advance and subsequently retract fifty- four millimeters (54 mm), the degree of angulations between pusher link tube 240 and elongated pusher tube 230 is approximately fourteen and ten-hundredths of a degree (14.1°), and the degree of angulations between pusher end tube 250 and pusher link tube 240 is approximately eight and eight-hundredths of a degree (8.8°). Other degrees of angulation and length of advancement are also contemplated. Slots 235, 245 are configured to receive opposed tabs 246, 256 formed on respective proximal ends 240a, 250a of pusher link tube 240 and pusher end tube 250, respectively, to maintain elongated pusher tube 230, pusher link tube 240 and pusher end tube 250 of pusher linkage 220 in lateral alignment during articulation of pusher link tube 240 relative to elongated pusher tube 230 and during articulation of pusher end tube 250 relative to pusher link tube 240, respectively. A distal end 250b of pusher end tube 250 is configured to selectively engage a proximal end of pusher back 310 (FIG. 21). In particular, distal end 250b includes an enlarged portion 254 defining a pair diametrically opposed openings and slots 253a, 253b (FIG. 23) configured to selectively receive engagement members 312 (FIG. 21) formed on pusher back 310. Pusher back 310 forms part of staple assembly 300 and will be discussed in greater detail below. Distal end 250b of pusher end tube 250 further includes spacers 258 extending radially outward to maintain pusher end tube 250 centered within distal end 30b of outer tube 30.

Pusher linkage 220 defines a hollow channel 221 (FIG. 18) for slidably receiving the approximation assembly 100. Although not shown, it is contemplated that any of elongated pusher tube 230, pusher link tube 240 and pusher end tube 250 may include an annular channel formed thereabout to receive an O-ring seal (not shown) to seal the space between pusher linkage 220 and an internal wall of outer tube 30. It is also contemplated that approximation assembly 100 may include one or more springs for biasing elongated pusher tube 230 proximally to a retracted position. In an embodiment, a spring is positioned between a proximal end of outer tube 30 and extensions 224a, 224b on proximal end 230a of elongated pusher tube 230.

Referring back to FIGS. 14-20, when firing trigger 202 is actuated, i.e., pivoted about pivot member 208, firing link 210 is moved proximally until pivot member 216 engages an abutment surface 154 (FIG. 8) formed on screw stop 150. Screw stop 150 is axially fixed to screw 120 in a manner to be described in detail below. Thereafter, firing trigger 202 is pushed distally to advance pusher linkage 220 distally. As noted above, although not shown, approximation assembly 200 may include a spring against which elongated pusher tube 230 of pusher linkage 220 is biased. Since distal end 250b of pusher end tube 250 of pusher linkage 220 is connected to pusher back 310, actuation of firing trigger 202 effects advancement of pusher back 310 within staple assembly 300 to eject staples "S" from staple assembly 300 in a manner to be described below.

Staple assembly 300 will now be described in detail with respect to FIGS. 21-32. Referring initially to FIG. 21, staple assembly 300 includes a shell 302, a pusher back 310, a cylindrical knife 320 and a staple guide 330. Shell assembly 302 includes an outer housing portion 304 and an inner guide portion 306 having ribs 306a (FIG. 25) for mating with splines 62 on anvil center rod 54 (FIG. 33). Outer housing portion 304 defines a throughbore 305 and includes a distal cylindrical section 304a, a central conical section 304b and a proximal smaller diameter cylindrical section 304c. In some embodiments, a plurality of openings (not shown) is formed in conical section 304b, each openings being dimensioned to permit fluid and tissue passage during operation of the device. With reference to FIGS. 24-27, a pair of diametrically opposed flexible cantilevered engagement members 308 are formed on proximal cylindrical section 304c of shell 302. Engagement members 308 are positioned to be selectively received in openings 33a (FIG. 22) which are defined in distal end 30b of outer tube 30 to selectively secure shell 302 to elongated body 30. Engagement members 308 each include a catch 308a formed on a proximal end thereof configured to be received within openings 33a formed in distal end 30b of outer tube 30 and at least one protrusion such as release tab 308b formed on a distal end thereof configured to be received within a portion of distal end 30b of outer tube 30 such as slots 33b formed in distal end 30b of outer tube 30. Simultaneous radially inward pressure on release tabs 308b bias engagement members 308 radially inward, thereby disengaging catches 308a from within openings 33a and permitting separation of staple assembly 300 from elongated body 30. In this manner, shell 302 of staple assembly 300 may be removed from surgical device 10 subsequent to use and stapling device 10 may be reloaded with another staple assembly 300 and reused. Shell 302 further includes an orientation tab 309 (FIG. 24) configured to be received within orientation slot 35 formed in distal end 30b of outer tube 30. Although not shown, it is also envisioned that engagement members 308 may be positioned on the distal end 30b of outer tube 30 and openings 33a may be positioned on the proximal end of shell 302 to selectively secure shell 302 to elongated body 30.

With particular reference to FIG. 21, pusher back 310 includes a central throughbore 311 which is slidably positioned about inner guide portion 306 of shell 302. Pusher back 310 includes a distal cylindrical section 310a which is slidably positioned within distal cylindrical section 304c of shell 304, a central conical section 310b and a proximal smaller diameter cylindrical section 310c. With reference to FIGS. 21-32, the proximal end of pusher back 310 (FIG. 21) includes engagement members 312 which are configured to selectively engage distal end 250b of pusher end tube 250 of linkage assembly 220 of stapling assembly 200. In particular, engagement members 312 each include a catch 312a and a cantilevered body portion 312b. Catches 312a are configured to be received within openings 253a formed in distal end 250b of pusher end tube 250 (FIG. 23). As shown in FIGS. 30-32, body portion 312b of each engagement members 312 is aligned with a respective slot 253b and engagement member 308 on shell 302. When release tabs 308b formed on engagement members 308 are depressed radially inward, as indicated by arrows "A" in FIG. 32, engagement members 308 press radially inwardly against body portion 312b of engagement members 312. The inward flexing of engagement members 312 caused by engagement members 308 disengages catches 312a from within openings 253a in pusher end tube 250. In this manner, pusher back 310 may be separated from staple pusher assembly 200 of surgical device 10 simultaneously with the separation of shell 302 from outer tube 30 to permit replacement of staple assembly 300.

With reference again to FIG. 21, the distal end of pusher back 310 includes a pusher 314. Pusher 314 includes a plurality of distally extending fingers 314a dimensioned to be slidably received within slots 331 formed in staple guide 330 to eject staples "S" therefrom. Cylindrical knife 320 is frictionally retained within the central throughbore of pusher back 310 to fixedly secure knife 320 in relation to pusher 314. Alternately, knife 320 may be retained within pusher back 310 using adhesives, crimping, pins, etc. A distal end of knife 320 includes a circular cutting edge 322.

As will be discussed in further detail below, in operation, when pusher linkage 220 is advanced distally in response to actuation of firing trigger 202, pusher back 310 is advanced distally within shell 302. Advancement of pusher back 310 advances fingers 314a through slots 331 of staple guide 330 to advance staples "S" positioned within slots 331 and eject staples "S" from staple guide 330 into staple deforming pockets 67 of anvil 68. Since knife 320 is secured to pusher back 310, knife 320 is also advanced distally to core tissue as will be described in more detail below.

Anvil assembly 50 will now be described with reference to FIGS. 33 and 34. An example of an anvil assembly is described in the Milliman Ί87 patent, the contents of which has been previously incorporated herein by reference in its entirety.

Briefly, anvil assembly 50 includes an anvil head assembly 52 and an anvil center rod assembly 54. Anvil center rod assembly 54 includes anvil center rod 56 which defines a bore 51 defined by a plurality of flexible arms 58. Bore 51 is dimensioned to receive anvil retainer 140. The distal ends of each of flexible arms 58 include an internal shoulder (not shown) dimensioned to releasably engage anvil retainer 140. A plurality of splines 62 are formed about center rod 56 and are dimensioned to be received within grooves 306a (FIG. 25) in staple assembly 300 to align anvil assembly 50 within staple assembly 300 during approximation of anvil assembly 50 and staple assembly 300. Center rod 56 also includes an annular recessed portion 55 to facilitate grasping of anvil assembly 50 by a surgeon with a grasper.

Referring also to FIG. 21, rigid bushing 340 is supported in the proximal end of inner guide portion 306 of shell 302. Bushing 340 defines a throughbore dimensioned to slidably receive anvil retainer 140 (FIG. 4) and center rod 56 of anvil assembly 50 (FIG. 33). Bushing 340 provides lateral support for flexible arms 58 of center rod 56 when the anvil assembly 50 has been approximated to prevent outward movement of arms 58 after arms 58 have been withdrawn into bushing 340 to prevent disengagement of anvil assembly 50 from anvil retainer 140. In the unapproximated position, flexible arms 58 of center rod 56 are positioned externally of bushing 340 to permit removal of anvil assembly 50 from retainer 140.

Although not shown, stapling device 10 (FIG. 1) may include an indicator positioned on the housing 20 having indicia, e.g., color coding, alpha-numeric labeling, etc., to identify to a surgeon whether stapling device 10 is approximated and is ready to be fired. In an embodiment, the indicator has a bulbous or convex shape which extends outwardly from a top surface of handle sections 20a, 20b and is easily viewable by a surgeon from the top and sides of the stapling device. Although not shown, stapling device 10 may also include a firing lockout member to prevent movement of firing trigger 202 of stapling assembly 200 unless stapling device 10 is approximated and in a position ready to be fired. Although not shown, stapling device 10 may further include a tactile indicator mechanism to provide an audible indication that stapling device 10 has achieved a given position. Alternatively, other types of indicators may be used with the stapling device 10 including those described in the Milliman Ί87 and Gresham '444 patents.

The operation of surgical stapling device 10 will now be described in detail with reference to FIGS. 35-43. With reference initially to FIGS. 35-39, surgical stapling device 10 is illustrated in an unapproximated or open position prior to attachment of anvil assembly 50 to anvil retainer 140 of approximation assembly 100. As noted above, surgical stapling device 10 may include a spring (not shown) for biasing linkage assembly 220 of staple pusher assembly 200 proximally. In particular, the spring would engage extensions 224a, 224b on proximal end 230a of elongated pusher tube 230 to urge pusher linkage 220 to its proximal-most position in which proximal end 230a of pusher tube 230 abuts screw-stop 150. During attachment of anvil assembly 50 (FIGS. 33 and 34) to anvil retainer 140, anvil retainer 140 (FIG. 9) is positioned within bore 51 of center rod 56 of anvil assembly 50. Flexible arms 58 deflect outwardly to accommodate center rod 56. Center rod 56 is advanced onto anvil retainer 140 until internal shoulder (not shown) of flexible arms 58 passes over annular protrusion 146 (FIG. 9) formed on anvil retainer 140. At this point, resilient legs 58 releasably engage anvil retainer 140. The position of the remaining components of stapling device are not affected by attachment of anvil assembly 50 to anvil retainer 140 and remain as described above and shown in FIGS. 35-39.

Turning to FIGS. 40 and 41, surgical stapling device 10 is illustrated with anvil assembly 50 attached to anvil retainer 140 and the anvil assembly 50 in an approximated or closed position. As discussed above, anvil assembly 50 is moved to the approximated or closed position by rotating rotation knob 102 in the direction indicated by arrow "B" in FIG. 40. Rotation of knob 102 causes cylindrical sleeve 210 to rotate to move pin 216 along substantially helical channel 121 of screw 120. Movement of pin 216 along helical channel 121 causes screw 120 to translate proximally within sleeve 210. Distal end 120a of screw 120 is connected to screw extensions 130 which are fastened at their distal ends to anvil retainer 140. As such, retraction of screw 120 within sleeve 210 is translated into proximal movement of anvil retainer 140 and anvil assembly 50. It is noted that when anvil assembly 50 is approximated, flexible legs 58 of center rod 56 are drawn into bushing 309 to lock legs 58 onto anvil retainer 140. It is envisioned that channel 32 may be of a constant pitch and/or curvature or an increasing or decreasing pitch and/or curvature.

With reference now to FIGS. 42 and 43, handle portion 12 of surgical stapling device 10 (FIG. 1) is illustrated during the firing stroke of firing trigger 202. As trigger 202 is compressed towards housing 20 in the direction indicated by arrow "C" in FIG. 42, pivot member 216 engages abutment surface 154 on screw stop 150 and firing trigger 202 is pushed distally. As discussed above, the distal end of firing trigger 202 is connected to the proximal end of pusher linkage 220. Accordingly, as firing trigger 202 is moved distally, elongated pusher tube 230, pusher link tube 240 and pusher end tube 250 of pusher linkage 74 are moved distally in the direction indicated by arrow "D" in FIG. 43 to effect advancement of pusher back 310 within staple assembly 300. Fingers 314a (FIG. 21) of pusher back 310 engage and eject staples "S" from staple guide 330. Cylindrical knife 320 is moved concurrently with pusher back 310 such that knife 320 moves into engagement with a cutting ring 64 and backup plate 66.

Anvil assembly 50 may be unapproximated away from staple assembly 300 and separated from stapling device 10 in a reverse manner. In particular, firing trigger 202 is pivoted away from housing 20 to retract pusher linkage 202 of stapling assembly 200 thereby retracting pusher back 310 of staple assembly 300. Then approximation knob 102 is turned in an opposite direction from that required to approximate anvil assembly 50, to unapproximate anvil assembly 50. Anvil assembly 50 may then be separated from stapling device 10. Once anvil assembly 50 is separated from stapling device 10, staple assembly 300 may be removed from body portion 14 (FIG. 1) in the manner discussed above. During a procedure on a patient, it is envisioned that stapling device 10 may be used multiple times by replacing staple assembly 300 after each use.

Stapling device 10 (FIG. 1) is used to perform circular anastomoses. Typically, circular anastomoses are required during procedures for removing a portion of a diseased vessel such as the colon or the intestine. During such a procedure, the diseased portion of the vessel is removed from the diseased vessel and the end portions of the remaining first and second vessel sections are joined together using the stapling device 10. Circular anastomoses are also required in a variety of other surgical procedures such as in gastric bypass procedures. The use of stapling device 10 will now be described. In use, stapling device 10 (FIG. 1) is operated in a manner substantially similar to a traditional circular stapler. Prior to removing a diseased vessel portion from a diseased vessel, anvil assembly 50 (FIG. 1) with a removable trocar (not shown) attached thereto is positioned in the first vessel section on a first side of the diseased portion. A removable trocar which is suitable for use with the anvil assembly 50 is disclosed in the Gresham '444 patent which, as discussed above, is incorporated herein by reference in its entirety. After the diseased vessel portion is removed and open ends of the first and second vessel sections have been sutured, the distal end of surgical device 10 is positioned in the second vessel section on the other side of the diseased portion which has been removed. At this time, the removable trocar is pushed through the suture line in the end of the first vessel section and removed from anvil assembly 50. Next, the end of anvil retainer 140 is pushed through the suture line in the second vessel section and is joined to center rod 54 of the anvil assembly 50. Stapling device 10 may now be approximated and fired in the manner discussed above to join the ends of the first and second vessel sections and core out any tissue obstructing the vessel lumen (FIG. 43).

With reference again to FIGS. 1-4, as discussed above, stapling device 10 is configured to be sterilized to facilitate use of stapling device 10 on a plurality of patients on different occasions. To permit reuse of stapling device 10, the components of stapling device 10 must either be sterilized or disposed of. Following use, staple assembly 300 is disengaged from outer tube 30 and approximation assembly 200 in the manner discussed above. Next handle sections 20a, 20b of housing 20 are separated to permit removal of approximation assembly 100 and staple pusher assembly 200. As approximation assembly 100 extends through staple pusher assembly 200, both approximation assembly 100 and staple pusher assembly 200 are removed from housing 20 simultaneously. Approximation assembly 100 is then removed from within pusher linkage 220 of staple pusher assembly 200 and the components of each of approximation assembly 100 and staple pusher assembly 200 are separated to permit sterilization thereof. For example, elongated pusher tube 230, pusher link tube 240 and pusher end tube 250 may be separated from each other to facilitate sterilization pusher linkage 220 of staple pusher assembly 200. Screw 120 may also be separated from rotatable sleeve 110 to facilitate sterilization of approximation assembly 100. Handle sections 20a, 20b of housing 20 and outer tube 30 may also be sterilized. Once all of the components are sterilized, stapling device 10 may be reassembled, including attaching a fresh staple assembly 300 to sterilized outer tube 30 and approximation assembly 200, and reused.

It is noted that because staple assembly 300 can be easily separated from outer tube 30 and approximation assembly 100 by pressing on release tabs 308b (FIG. 32), and replaced with a fresh staple assembly 300, stapling device 10 may be used to perform multiple operations during a single surgical procedure on a single patient without sterilizing stapling device 10.

It will be understood that various modifications may be made to the embodiments disclosed herein. Therefore, the above description should not be construed as limiting, but merely as exemplifications of preferred embodiments. Those skilled in the art will envision other modifications within the scope and spirit of the claims appended hereto. For example, although the description refers exclusively to staples, it is envisioned that staples may include different types of tissue fasteners including two-part fasteners. In a stapling device for applying two-part fastener, the anvil assembly of the stapling device would support one part of each two-part fastener.

Claims

WHAT IS CLAIMED IS:

1. A surgical stapling device comprising:

a housing;

an outer tube extending distally from the housing having a proximal end configured for operable connection with the housing and a distal end;

a disposable staple assembly releasably supported on a distal end of the outer tube, the staple assembly including a shell movably supporting a pusher back, and a plurality of fasteners, the pusher back being movable with the shell to eject the plurality of fasteners from the disposable staple assembly;

an approximation assembly operably received within the housing, the approximation assembly including an anvil retainer configured to releasably engage an anvil assembly, the approximation assembly being operable to approximate the anvil assembly and the staple assembly; and

a staple pusher assembly extending from within the housing to the staple assembly, the staple pusher assembly releasably connected to the pusher back of the staple assembly and operable to effect movement of the pusher back within the shell, wherein the staple assembly includes at least one release tab which is movable to effect separation of the staple assembly and the outer tube.

2. The surgical stapling device of claim 1, wherein the approximation assembly and the staple pusher assembly are selectively removable from within the housing.

3. The surgical stapling device of claim 1, wherein the housing includes a first housing section and a second housing section releasably coupled to the first housing section.

4. The surgical stapling device of claim 3, wherein the first and second housing sections are configured to be separated to provide access to an interior of the housing.

5. The surgical stapling device of claim 1, wherein the staple pusher assembly is configured to be sterilized.

6. The surgical stapling device of claim 1, wherein the staple pusher assembly includes a pusher linkage for effecting ejection of the staples from the staple assembly.

7. The surgical stapling device of claim 1, wherein the outer tube includes at least one opening and the shell includes at least one engagement member positioned to be received within the at least one opening to releasably secure the shell to the outer sleeve.

8. The surgical stapling device of claim 7, wherein each of the at least one engagement members includes a release tab which is depressible to effect disengagement of the shell and the outer tube.

9. The surgical stapling device of claim 8, wherein the at least one engagement member includes two engagement members and the at least one opening includes two openings, each opening being configured to receive a respective one of the engagement members.

10. The surgical stapling device of claim 1, wherein the pusher back includes at least one cantilevered engagement member and the staple pusher assembly includes a pusher tube defining at least one opening positioned to receive the at least one engagement member to releasably secure the pusher back to the pusher tube.

11. The surgical stapling device of claim 10, wherein the at least one cantilevered engagement member includes two cantilevered engagement members and the at least one opening includes two openings, each of the opening being positioned to receive a respective one of the engagement members.

12. The surgical stapling device of claim 8, wherein the pusher back includes at least one cantilevered engagement member and the staple pusher assembly includes a pusher tube defining at least one opening positioned to receive the at least one cantilevered engagement member to releasably secure the pusher back to the pusher tube.

13. The surgical stapling device of claim 12, wherein the at least one engagement member of the shell is positioned about the at least one cantilevered engagement member of the pusher back such that the release tab is depressible to move the engagement member of the shell into contact with the cantilevered engagement member of the pusher back to deflect the cantilevered engagement member of the pusher back inwardly to effect disengagement of the pusher back from the pusher tube.

14. A surgical stapling device comprising:

a housing; and

an approximation assembly operably received within the housing, the approximation assembly including:

a rotatable sleeve defining an internal notch;

a screw configured to be longitudinally advanced and retracted relative to the rotatable sleeve, the screw includes a plurality of substantially helical thread sections and an unthreaded space between each of the helical thread sections, wherein each of the helical thread sections are configured to selectively engage the internal notch in the rotatable sleeve; and

a first spring disposed distal of the screw for biasing the screw proximally, wherein the first spring urges a proximal face of an adjacent helical thread section into engagement with the internal notch as each helical thread section disengages the internal notch.

15. The surgical stapling device of claim 14 further including a second spring disposed proximal of the screw for biasing the screw distally.

16. The surgical stapling device of claim 15 wherein the force applied to the screw by the first spring is greater then the force applied to the screw by the second spring.

17. A surgical stapling device comprising:

a housing;

an outer tube extending distally from the housing having a proximal end configured for operable connection with the housing and a distal end; and a staple pusher assembly extending from within the housing to the staple assembly, the staple pusher assembly releasably connected to a pusher back of a staple assembly and operable to effect movement of the pusher back within a shell of the staple assembly, wherein the staple pusher assembly includes a pusher linkage for effecting ejection of the staples from the staple assembly, wherein the pusher linkage includes a plurality of pusher tubes configured to articulate relative to each other.

18. The surgical stapling device of claim 17, further wherein the pusher tubes include a flange extending therefrom and forming a recess.

19. The surgical stapling device of claim 18, wherein the flange defines a slot to receive a tab of an adjacent pusher tube.

20. The surgical stapling device of claim 17, wherein the pusher tubes are at least one of straight and curved.